package cn.layfolk.nio;

import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.util.Arrays;

/**
 * @Author 王津
 * @Date 2020/9/23
 * @Version 1.0
 */
//Scattering:将数据写入到buffer时，可以采用buffer数组，依次写入 [分散]
//Gatgering:从buffer读取数据时，可以采用buffer数组，依次读
public class _08ScatteringAndGatheringTest {
    public static void main(String[] args)  throws  Exception{

        //使用 ServerSocketChannel 和 SokcetChannel 网络
        ServerSocketChannel serverSocketChannel = ServerSocketChannel.open();
        InetSocketAddress inetSocketAddress = new InetSocketAddress(7000);

        //绑定端口到socket，并启动
        serverSocketChannel.socket().bind(inetSocketAddress);

        //创建buffer数组
        ByteBuffer[] byteBuffers = new ByteBuffer[2];
        byteBuffers[0] = ByteBuffer.allocate(5);
        byteBuffers[1] = ByteBuffer.allocate(3);

        //等客户端连接(telnet)
        SocketChannel socketChannel = serverSocketChannel.accept();
        int messageLength = 8; //假定从客户端接受8个字节
        //循环的读取
        while (true) {
            int byteRead = 0;
            while (byteRead < messageLength) {
                long l = socketChannel.read(byteBuffers);
                byteRead += l; // 累计读取的字节数
                System.out.println("byteRead=" + byteRead);
                //使用流打印，看看当前的这个buffer的position和limit
                Arrays.asList(byteBuffers).stream().map(buffer -> "position=" + buffer.position() + ",limit=" +
                        buffer.limit()).forEach(System.out::println);
            }
            //将所有的buffer进行flip
            Arrays.asList(byteBuffers).forEach(buffer->buffer.flip());

            //将数据读出显示到客户端
            long byteWrite = 0;
            while (byteWrite < messageLength){
                long l = socketChannel.write(byteBuffers);
                byteWrite+=l;
            }

            //将所有的buffer进行clear
            Arrays.asList(byteBuffers).forEach(buffer->{
                buffer.clear();
            });
            System.out.println("byteRead="+byteRead+",byteWrite="+byteWrite+",messageLength="+messageLength);
        }

    }
}
